...Oh yeah, make sure it's a .45acp.
I don't disagree in general with this statement, the .45 ACP being the quintessential "manstopper" in hand gun cartridges. But I wouldn't bet the farm on it either. A couple of anecdotes:
1. Capt. W.E. Fairbairn, of Shanghai Police/WWII combatives/Commandos fame, tells the story of a Chinese bandit that continued to charge a police officer who shot him seven times at close quarters with a .45 ACP.
2. One of the guys at my former combat pistol club was a graduate of several courses at Gunsite, back in the Jeff Cooper days. As such, he very much swore by the .45 ACP (Col. Cooper's opinion of the M1911/.45 ACP is well known). He used to josh me about my 9mm being a ".45 set on stun".
On the same day I walked into club practice with my brand new Sig/Sauer P226 in .40 S&W,
HE walks in with another brand new P226,
but in 9mm. After joshing him a while, I finally asked him why this rather dramatic change of opinion. He said that it was due to his own anecdotal survey of various folks, including paramedics, Navy SEALs, police officers, etc. He said that the conclusion he came to was that the
REAL manstopper was the rifle. The hand gun was just a stop gap measure, not as good as a rifle but better than empty hands. As such, shot placement and high capacity (In order to have more chances of getting that one, crucial hit while under the stress of an lethal force encounter), in the opinion of the people he talked to, seemed to be of much greater importance than the power of the hand gun round, which is really marginal at best.
BTW, my personal choice of the .40 S&W is because it struck me as a very nice compromise between power, round capacity and manageable compactness.
Brad "butterfly" Burklund (From these forums) sent me a very long, but very interesting article, a couple of years back by an avid handgunner who'd been a police officer and is currently an autopsy technician. What he had to say in his article tended to bear out my deduction, as he stated that, anecdotally, the three most lethal rounds (Based on the people he saw laid out for autopsy) were the .45 ACP, the .357 magnum and the .40 S&W.